1. Field of the Invention
The present invention relates to a shared information system in a network.
2. Description of the Related Art
With the wide spread of the Internet and mobile information terminals such as mobile telephones capable of utilizing Internet services including electronic mail, etc., the expectations on the mobile information terminals for the information distribution have been raised.
However, to activate the information distribution such as sharing the same information among a plurality of mobile information terminals, inheriting the same information among a plurality of different mobile information terminals, etc., increasing the number of mobile information terminals is an essential condition, but one of the factors interfering with the increase of the number of mobile information terminals is the problem of the financial burden in using information.
Additionally, information itself has the problems to be solved such as the limitations of use range by the “use restrictions (membership)” in using the information, the appropriate countermeasures to be taken for the “intellectual property rights (copyright protection)”, etc.
FIG. 1 shows the concept of the target information distribution service system.
In the configuration shown in FIG. 1, a portable mobile information terminal 10 and an information terminal 11 used by a service user are connected to a mobile network 12 or an access network 13. The mobile network 12 and the access network 13 are connected to a trunk network 14. A contents provider 15 and an ASP 16 having a private enterprise network 17 are connected to the trunk network 14, and a service is provided for a service user. The private enterprise network 17 is an individual network with which the ASP 16 has made a contract to provide the service.
In the information distribution service, there are a service user, a member that the service user enters for sharing or inheriting information, an ASP (server system) for realizing the service, and a number of information providers. Each information provider provides information browsed or enjoyed by the service user.    (1) The service user and the server system operation company enter a contract on the use of the service.    (2) The server system provides a service such as sharing and inheriting information, etc. for a mobile information terminal entered as a target terminal of the service user based on a specified request condition with the prescribed conditions (intellectual property rights, etc.) of the information taken into account.    (3) The server system makes a payment to protect the target mobile information terminal from the financial burden such as a communication cost, etc. charged for the information distribution such as sharing and inheriting information, etc.
The conventional technology for the system realizing the above mentioned information distribution is disclosed by the patent documents 1 through 3. The patent document 1 discloses the technology of extracting an IP address and a network login ID from an access log, and charging for services. The patent document 2 discloses the technology of adding attribute data to copyright data, and charging for services based on the obtained data. The patent document 3 discloses the technology of accumulating data generated by users, and sharing, retrieving, and distributing the data among the users.    [Patent Document 1] Japanese Published Patent Application No. 2001-344526    [Patent Document 2] Japanese Published Patent Application No. 2002-150008    [Patent Document 3] Japanese Published Patent Application No. 2004-164372
The financial burden such as a communications rate, etc. to a receiver of information is one of the impediments to the activation of the information distribution in a network, and it is necessary to minimize the economic factor, that is, the psychological factor, in receiving information.
The “intellectual property rights” of information itself is important and indispensable for protection against illegal information distribution and for copyright protection. That is, to activate the information distribution, a solving device for the case in which information to be distributed is copyright-protected by “transfer disabled”, “copyguarded”, etc. is required.
Furthermore, when information which has once been downloaded for use by a service user is downloaded again each time a different mobile information terminal downloads the same information, a time burden and an economic burden newly arise.
That is, although a mobile information terminal being used is changed to another terminal during receiving information, the information being received can be inherited by the other terminal, thereby further improving the convenience.